The present invention relates generally to improving the performance of a radio frequency identification (RFID) tunnel reader with boxes of items, such as clothing, packed close together. More particularly, the present disclosure relates to a read tunnel device for scanning a plurality of cartons of high density packaged items moving through an enclosure via a conveyor belt.
Radio frequency identification (RFID) tags are electronic devices that may be affixed to items whose presence is to be detected and/or monitored. The presence of an RFID tag, and therefore the presence of the item to which the RFID tag is affixed, may be checked and monitored by devices known as “readers” or “reader panels.” Readers typically transmit radio frequency signals to which the RFID tags respond. Each RFID tag can store a unique identification number. The RFID tags respond to reader-transmitted signals by providing their identification number and additional information stored on the RFID tag based on a reader command to enable the reader to determine an identification and characteristics of an item.
Currently, the need for the ability to scan RFID transponders in automated environments has caused the creation of a scanning tunnel or enclosure (i.e., a RFID dynamic tunnel scanner). Different manufacturers may take different approaches to scanning these transponders. Typically, an enclosure uses a combination of absorber material to attenuate radio frequency energy and a read chamber central to the enclosure that projects a read zone. Thus, the read chamber uses an absorber method that directs the main flow of energy normal to the antenna plain, creating the read zone.
Furthermore, the main challenge in utilizing a RFID dynamic tunnel scanner is the inability to capture all of the inlay/transponders applied to each individual item within a given carton. Specifically, spacing between cartons, speed of the conveyor equipment, power supplied by the RFID reader, among other parameters are all very difficult to manage to achieve a 100% read rate without creating over-read conditions whereby inlays from adjacent cartons upstream or downstream of the intended carton are read as well. The other end of the spectrum of course is not reading all of the tags properly.
Furthermore, the performance of RFID tags in a carton can be effected by the properties of the product, for example, presence of metal items and their dielectric properties. Another significant factor is proximity between tags, which can cause reduction of performance. Generally, the worst case scenario is when an array of RFID tags inside a carton are in a relatively fixed position with respect to each other; then some RFID tags may have greater levels of degradation of performance than others and may not be read in transit through a scanning tunnel.
The present invention discloses a read tunnel device that improves the readability of items in a carton passing through a tunnel reader. The device both changes the relative arrangement of the RFID tags and the position of the carton with respect to the read antenna dynamically as the carton transits the read zone. The device induces a rotation of the carton in the vertical axis (or the other axis) as it travels through the reader.